This presentation from NSA’s Mathematics Research Group, dated 21 August 2008 provides an introduction to the XKeyScore system’s data sources and fingerprinting capabilities: see the SVT article FRA part of top-secret hacker project, 11 December 2013.

xks-cipher-detection-and-you-p1-normal.gif:
﻿TOP SECRET//COMINT//REL TO USA, FVEY
, Cipher Detection, and You!
Mathematics Research Group
21 August 2008
TOP SECRET//COMINT//REL TO USA, F...

This undated presentation from GCHQ’s PTD (Penetrating Target Defences) unit gives an overview of BULLRUN efforts to defeat encryption: see the Der Spiegel story Prying Eyes: Inside the NSA’s War on Internet Security, 28 December 2014.

﻿TOP SECRET STRAP1
BULLRUN
PTD Lead for Special Operations and Policy
PTD "We penetrate targets' defences."
This information is exempt from disclosure under the Freedom of Information A...

This NSA document from January 2013 lists the codenames of those agency activities sufficiently sensitive to qualify as “exceptionally controlled information”: see the Intercept article Core Secrets: NSA Saboteurs in China and Germany, 10 October 2014.ah

This NSA presentation dated 27 October 2009 outlines the use of intercepted IPSec VPN data within the agency: see the Der Spiegel story Prying Eyes: Inside the NSA’s War on Internet Security, 28 December 2014.

This undated page from NSA’s internal WikiInfo describes VALIANTSURF “the coverterm for the development of Data Network Cipher (DNC) exploitation capabilities in TURMOIL”: see the Der Spiegel story Prying Eyes: Inside the NSA’s War on Internet Security, 28 December 2014.

﻿VALIANTSURF - Wikiinfo
The accredited security level of this system is: TOP SECRET//SI-GAMMA/TALENT KEYHOLE//ORCON/PROPIN/RELIDO/REL TO USA, FVEY *
TOP SECRET1/SI/10RCON1REL TO USA, FVEY
...

A classification guide on the NSA’s Project BULLRUN goals and capabilities in decryption: see the Guardian article Revealed: how US and UK spy agencies defeat internet privacy and security, 5 September 2013.